决策树方法在一次历史异常雷电活动中的预报能力检验

The Forecast Ability Test of Decision Tree Method in an Abnormal Lightning Activity

利用ncep1°×1°再分析资料和四川闪电定位仪监测网的监测资料,基于四川雷电潜势预报决策树的三类预报因子,针对2008年9月22～25日四川盆地西北部连续性雷电活动过程,重点分析了连续性雷电活动的环流背景和主要天气影响系统、热力结构特征、动力结构特征,检验了基于决策树方法筛选出的雷电潜势预报因子对连续性雷电活动的预报能力.结果表明：1）“9·23”连续性雷暴天气过程存在对流性雷暴以及副高和地面冷空气共同作用下形成的雷暴时段.雷暴区内始终存在着高能不稳定的热力条件,具有“对流层中低层正涡度、对流层高层负涡度”的典型雷暴动力结构.2）雷电潜势预报决策树的三大类预报因子能较好地预报本次雷电活动.

Using NCEP1°×1° reanalysis data and lightning monitoring data of Sichuan lightning location monitoring network system, Based on three kinds of forecast factors of Sichuan lightning potential forecasting decision tree, in allusion to the persistent lightning activity process in the northwestern Sichuan Basin of September 23rd to September 25th ,2008, special anal- ysis the circulation background of persistent lightning activity and main weather system, thermal structure characteristics, dy- namic characteristics, test the prediction ability of lightning potential forecasting factor which selected by decision tree method on the persistent lightning activity process. The result shows ： 1 ） in persistent thunderstorm weather process of September 23rd, there are convective thunderstorm and thunderstorm period under the common action of subtropical high and surface cold air. Thunderstorm area always has a high - energy unstable thermal condition, which has typical characteristic of thunderstorm dynamic by the middle and low troposphere positive vorticity, negative vorticity in the upper troposphere. 2） Three kinds of forecast factors of lightning potential forecasting decision tree can effectively forecast the lightning activity.